30 SURFACE GEOLOGY. 



the tops of terraces and beaches, and have given the result on this section, 'which 

 commences at the highest part of the sandy plain lying between Albany and 

 Schenectady, and, following the railroad, terminates at the highest point on the 

 road of the Hoosac range. The horizontal scale is so small compared with the 

 vertical, that the section is very much distorted, and gives but a poor idea of the 

 country passed over. On the east side of the Hudson, after rising to the third 

 broad terrace, the ascent is gradual most of the way to the State line between New 

 York and Massachusetts, a distance of 38 miles. Between that point and Pitts- 

 field, eleven miles, the sui'face is chiefly covered with unmodified drift. Thence 

 eight miles to Hinsdale, the drift is frequently covered by re-arranged drift, which 

 I suppose to have been modified by the ocean, beating against the side of Hoosac 

 Mountain. The same is true of the remaining five miles, which brings us to 

 Washington, on the summit level, and, as already explained, I have regarded the 

 sea action there as extending upwards above the railroad 200 feet. 



Though at each of the railroad stations where I took observations, I have repre- 

 sented a distinct beach on the section, it must not be supposed that such is the fact 

 at those places, while between them no beaches exist. I mean only to indicate 

 that beach materials exist at those places, but exactly how many distinct beaches 

 exist along the route, I am unable to say. That the whole of this inclined plane 

 once constituted the shore of a retiring ocean, I cannot doubt ; but how many 

 pauses there might have been in the vertical movement, so as to form marked 

 beaches, is a point I have not determined. 



At some of the stations of medium height, say at Chatham and East Chatham, 

 I noticed those irregular elevations and depressions of sand and gravel, which I 

 have already described as occurring among the highest of the perfect terraces, and 

 below the most distinct beaches. Prom this fact we must infer that at that par- 

 ticular level of the waters some peculiar action must have taken place, necessary 

 to produce these modified effects. I refer to those accumulations which I have 

 denominated Moraine Terraces. 



40. This section was taken by the aneroid barometer, on the west side of Genesee 

 river, in Mount Morris, which lies at the lower end of that remarkable gorge cut 

 by the river from Portage to that place. There is nothing very instructive in the 

 section. We see, however, that the terraces here are of great height, and they are, 

 also, in general quite broad. An enormous quantity of detrital matter has in past 

 ages been brought into the Genesee valley, and there are some quite instructive 

 facts in relation to former changes of river beds. But this subject I shall reserve 

 for my paper on Erosions. 



Terraces on Rivers and Lakes at the West in our Country. 



I have not had much opportunity to examine our western rivers and lakes with 

 reference to the surface geology of their banks. The Ohio did not seem to me 

 remarkable for its terraces, nor did the Great Kanawha. On them both we meet 

 occasionally with two terraces, sometimes three. The horizontal position of the 

 sandstone and limestone strata in the Western States, exposes one to error in this 



